The following description of the background of the invention is provided to aid in understanding the invention, but is not admitted to be, or to describe, prior art to the invention. All publications are incorporated by reference in their entirety.
Chemical oxidation of unwanted chemicals has been used for many decades. The use of oxidants such as chlorine bleach, hydrogen peroxide, potassium permanganate, potassium persulfate, sodium perborate and a host of other similar oxidizing chemicals dates from the 1800's. The science of chemical oxidation is similar to that of bleaching clothes. The two major differences between bleaching clothes and oxidizing undesirable chemicals are:                1) In bleaching clothes the oxidizing agent is applied at low concentration in hot water while in ground water treatment of chemicals, the concentrations of the oxidizing agent used are higher at the point of treatment and are in cold water.        2) In bleaching clothes the oxidants are selected so as not to impart color to the solution or to the clothes whereas in ground water remediation, discoloration of the soil is of lesser concern but the treated water color should not be affected.        
For decades technology has been sought to improve the effectiveness of oxidizing agents. An example of one improvement is the use of metal catalysts to increase the oxidizing effects of oxidizing agents. For example, the use of iron as a catalyst is described in a 1955 text book (Edwin S. Gould, “Inorganic Reactions and Structure”, Henry Holt and Company, 1955 pp. 76-78). The oxidative relationship between hydrogen peroxide permanganate and persulfate is also described.
Fieser and Fieser (Louis F. Fieser and Mary Fieser, “Reagents for Organic Synthesis”, John Wiley and Sons, 1967 pp. 472-476, 952-954, 1102) describe the use of iron salts with peroxide to make the so-called Fenton's Reagent citing the original paper by Fenton in 1894. It was found that chelates of iron work as well or better than iron alone and that other metal salts may also work. The Fiesers also discussed the metal catalysis of persulfate. However it was found that the oxidation did not proceed to completion. That is, specific reaction sequences are described leading from one series of chemicals to another. Specifically it was not shown that the reactions, for example of hydrocarbons and carbohydrates, led to complete oxidation of the materials to carbon dioxide and water. The present day aim of oxidizing technology for removal of pollutants can be described as follows:
1) To proceed as far as possible toward complete removal of the substrate species;
2) To proceed as rapidly as possible; and
3) To use as little reagent as possible.
The concept of using minimal reagent while providing efficient oxidation is especially important in treating chemicals in ground water or soils by oxidation where it is not desirable to leave the oxidant in the water or in the ground and to minimize the concentration of non native chemical species.
The use of chelated metals, specifically iron with a hydrogen peroxide liberating salt such as sodium perborate or sodium percarbonate is disclosed in U.S. Pat. No. 4,119,557 as part of an overall detergent formulation. In this patent the chelating agent using iron was shown to be superior to other metals such as copper and cobalt.
Recent applications related to ground water have been published. Many of these pregrant publications do not discuss the common chemistry surrounding bleaching. For example, U.S. PreGrant Publication 20020002983 A1 discusses the addition of iron chelates to ground water under buffered conditions. The main claim is to the use of the reagent solution comprising iron chelate and a pH buffering agent. U.S. Pat. No. 6,315,494 B1 dealing with soil remediation by permanganate oxidation discloses the use of metal catalysts.
With regard to bleaching compositions, further technology has ensued in making various forms of particles to be added to detergent formulations either with or without catalysts. For example, U.S. Pat. No. 5,902,783 describes a bleaching agent which is based on a silicate core and contains a peroxy material such as sodium percarbonate and a metal chelating agent in an organic compound. These materials are described for washing use and are undesirable in groundwater remediation as the materials would add more organic materials to the water being treated. Furthermore, these particles are described as being useful for incorporation in a box of detergent powder. U.S. Pat. No. 6,547,490 B1 describes similar types of particles except these are silicone coated rather than the silicone acting as a core. Both the silicone products and the silicates are not silica. The silicones are considered to be ground water contaminats.
It is important to distinguish the purpose of chemical oxidation from the process where the release of oxygen is to cause biological remediation of ground water contaminants or contaminants in soils. In the case of biological remediation the purpose is to feed the bacteria oxygen slowly over time and allow them to metabolize the contaminant. Oxidizing agents such as described previously for the direct chemical oxidation of the contaminants would be injurious to the microbes and defeat the purpose of the subsequent aerobic metabolism. When using chemical oxidation the possibility exists that the oxidation is unlikely to be complete so that the aquifer or soil must be left in a condition where the residual microbes on the edges of the treatment zone can effectively metabolize the residual oxidized materials and reoccupy their ecological niche in the treatment zone.